Code No. P0401: EGR Flow Insufficient <Euro5b>


OPERATION



  • Refer to Code No. P0102: Air Flow Sensor Circuit Low Input .
  • Refer to Code No. P0403: EGR Valve (DC Motor) Malfunction .
  • Refer to Code No. P0489: EGR Valve Position Sensor Circuit Low Input <Euro5b> .

FUNCTION



  • The engine-ECU monitors the EGR flow rate.

TROUBLE JUDGMENT


Check Conditions
  • Engine is running.
  • Battery positive voltage is 8 - 16 V.
  • Normal running (vehicle speed: 65 - 75 km/h, transmission: 5th <M/T>, D range <A/T>).
  • The intake air temperature is from 20 to 40 °C.
Judgment Criterion
  • The EGR flow rate is larger than target EGR flow rate by the rate that is more than the specified value.

PROBABLE CAUSES



  • Failed EGR passage (leakage and clogged EGR passage)
  • Harness damage in EGR valve circuit or loose connector contact
  • Failed EGR valve operation
  • Harness damage in air flow sensor circuit or loose connector contact
  • Failed air flow sensor (abnormal output characteristics)
  • Failed engine-ECU

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is the diagnosis code P0403 or P2413 set?
Inspection chart for diagnosis codes (Refer to ).
Go to Step 2.

STEP 2. Connector check: A-45 EGR valve assembly connector

Q. Is the check result normal?

Go to Step 3.

Repair or replace the connector.

STEP 3. Connector check: C-103 and C-105 engine-ECU connectors

Q. Is the check result normal?

Go to Step 4.

Repair or replace the connector.

STEP 4. Check harness between C-103 (terminal No. 115) engine-ECU connector and A-45 (terminal No. 6) EGR valve assembly connector.



  • Check output line for damage.

Q. Is the check result normal?

Go to Step 5.

Repair the damaged harness wire.

STEP 5. Check harness between C-103 (terminal No. 130) engine-ECU connector and A-45 (terminal No. 4) EGR valve assembly connector.



  • Check output line for damage.

Q. Is the check result normal?

Go to Step 6.

Repair the damaged harness wire.

STEP 6. Check harness between C-105 (terminal No. 81) engine-ECU connector and A-45 (terminal No. 2) EGR valve assembly connector.



  • Check earthing line for damage.

Q. Is the check result normal?

Go to Step 7.

Repair the damaged harness wire.

STEP 7. Check harness between C-105 (terminal No. 71) engine-ECU connector and A-45 (terminal No. 3) EGR valve assembly connector.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 8.

Repair the damaged harness wire.

STEP 8. Check harness between C-105 (terminal No. 57) engine-ECU connector and A-45 (terminal No. 1) EGR valve assembly connector.



  • Check output line for damage.

Q. Is the check result normal?

Go to Step 9.

Repair the damaged harness wire.

STEP 9. Check EGR valve itself.

  • Check EGR valve itself [Refer to GROUP 17 - Emission Control - Exhaust Gas Recirculation (EGR) System - EGR Valve (DC motor) Check ].

Q. Is the check result normal?
Go to Step 10.
Replace the EGR valve assembly.

STEP 10. Check EGR passage for deposits.

  • Check the EGR valve, the EGR pipe and the inside of the EGR cooler for deposits. (Refer to GROUP 17 - Emission Control - EGR Valve And EGR Cooler - Removal And Installation ).

Q. Is the check result normal?
Go to Step 11.
Cleaning or replace the EGR valve, EGR pipe and EGR cooler.

STEP 11. Connector check: A-135 air flow sensor connector.

Q. Is the check result normal?

Go to Step 12.

Repair or replace the connector.

STEP 12. Check harness between A-135 (terminal No. 4) air flow sensor connector and C-103 (terminal No. 155) engine-ECU connector.



  • Check earthing line for damage.

Q. Is the check result normal?

Go to Step 13.

Repair the damaged harness wire.

STEP 13. Check harness between A-135 (terminal No. 3) air flow sensor connector and C-103 (terminal No. 140) engine-ECU connector.



  • Check output line for damage.

Q. Is the check result normal?

Go to Step 14.

Repair the damaged harness wire.

STEP 14. Replace the air flow sensor.

  • After replacing the air flow sensor, re-check the trouble symptoms.

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, carry out the forcible DPF regeneration. (Refer to GROUP 17 - Emission Control - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).